Well, it did exist somewhat in the 70s and 80s, but mostly as Logan making moves on Jean and Scott getting jealous, while Jean... well, let's just say I have no idea what the writers were thinking. They probably needed a female perspective to write her better because I seriously can't believe a woman in real life would actually let that situation continue. In the 90s they dialed back on it after Jean's return in the late 80s with X-Factor and Scott and Jean's wedding in the early 90s. The Age of Apocalypse storyline kinda brought that issue back up, but only as an alternate timeline thing. It wasn't until the 2000 movies came out that the comics started really pushing that narrative, and that's when things starting going bad. Scott and Jean's characters were ruined during that time.